This meeting is dedicated to reviewing the understanding and insights on HIV pathogenesis since the initial discovery of the virus in 1983. It includes pioneer lectures from leaders in the field who were active 20 years ago. They will be presenting views on the future challenges in virology, immunology, epidemiology, and clinical science. [unreadable] [unreadable] The conference opens with keynote addresses covering the global perspective of HIV infection and aspects of cell biology and molecular biology involved in HIV replication. It then addresses HIV infection in a step-wise manner beginning with the interaction of the virus with the cell surface, the diversity of viral strains (including HIV-2) involved, and various intracellular events controlling replication. The immunologic responses include, in greater detail, information on the thymus and importantly, the role of the innate as well as adaptive immune systems. The presentations on HIV pathogenesis deal not only with the immune system, but also with other tissues of the body including the brain, gastrointestinal tract, and the kidney. These topics have not been given much attention in past Keystone conferences. Opportunistic infections and malignancies are also covered as part of the dedication to HIV pathogenesis. In addition, information obtained from highly exposed individuals, genetic polymorphisms and differences in response to HIV infection between men and women are considered. The role of accessory proteins and co-factors (e.g. hepatitis C and G) will also be discussed. [unreadable] [unreadable] This conference brings together outstanding researchers in several different scientific and medical fields to address aspects of HIV infection and disease including several topics that have not been considered in great detail by other Keystone conferences. Short talks will be encouraged to allow time for audience discussions on each of the topics scheduled. The presentations will permit attendees to appreciate and to understand what approaches need to be done to control HIV infection itself as well as its consequences. [unreadable] [unreadable]